1. Technical Field
The present disclosure relates to a method of manufacturing toner for use in electrophotographic image forming apparatuses such as copier, laser printers, and facsimile machines.
2. Description of Related Art
To meet increasing demand for higher image quality, electrophotographic toners have been developed to have a narrower size distribution and a spherical shape. Because spherical toner particles with a narrow size distribution each behave in the same manner when developing an electrostatic image, the resulting toner image has high microdot reproducibility. In particular, spherical toner particles having a narrow size distribution and a small particle diameter are difficult to reliably remove with a blade member when they are undesirably remaining on an image bearing member.
By contrast, irregular-shaped toner particles, generally having low fluidity, are easy to remove with a blade member. However, because such irregular-shaped toner particles behave unstably when developing an electrostatic image, the resulting toner image has low micro-dot reproducibility. Because irregular-shaped toner particles are transferred onto a transfer medium at a low filling rate, the resulting toner layer on the transfer medium has a low thermal conductivity. Such a toner layer having a low thermal conductivity cannot be fixed on the transfer medium at low temperatures, especially when fixing pressure is relatively small.
JP-H09-15903-A discloses a method of manufacturing toner including steps of mixing a binder resin and a colorant in a water-immiscible solvent, dispersing the resulting composition in an aqueous medium in the presence of a dispersion stabilizer, removing the solvent from the resulting suspension by applying heat and/or reducing pressure to form irregularities on the surfaces of the resulting particles, and spheroidizing or deforming the particles by applying heat. The resulting toner particles may have unstable chargeability because their shapes are irregular.
JP-2005-49858-A discloses a method of manufacturing toner including steps of dispersing a solvent dispersion comprising a resin and/or a precursor thereof and a filler in an aqueous medium to prepare a W/O dispersion, and removing the solvent from the W/O dispersion to prepare resin particles. The W/O dispersion includes oil droplets, each of which includes an accumulation layer of the filler. The resulting toner particles may be easily removable with a blade member (hereinafter “cleanability”) because they have irregular shapes due to the presence of the accumulation layer of the filler on their surface. However, such toner particles may not be fixed on a recoding medium at low temperatures due to the presence of the accumulation layer of the filler on their surface.
JP-2005-10723-A discloses a method of manufacturing toner including steps of dispersing an organic solvent solution or dispersion of toner components in an aqueous medium, introducing the resulting emulsion to a continuous vacuum defoaming device, and removing the organic solvent from the emulsion by applying shearing force. The resulting toner particles may be easily removable with a blade member, and may cause neither toner scattering in text images nor deterioration of line image reproducibility. However, in order to obtain spherical toner particles having a small particle diameter and a narrow particle diameter distribution, this method may be required to further improve the efficiency of organic solvent removal.
JP-H11-133665-A discloses a method of manufacturing toner including steps of dissolving binder resins comprising a urethane-modified polyester (i) and an unmodified polyester (ii) in a solvent, and dispersing the resulting solution in an aqueous medium. JP-H11-149180-A discloses a method of manufacturing toner including steps of elongating and/or cross-linking a polyester prepolymer (A1) having an isocyanate group with an amine (B) in an aqueous medium to obtain a resin (i). The resulting toner includes the resin (i) and another resin (ii) inactive with either (A1) or (B) as binder resins.
JP-2000-292981-A discloses a method of manufacturing toner in an aqueous medium. The resulting toner includes a high-molecular-weight resin (A) and a low-molecular-weight resin (B).
Each of the publications JP-H11-133665-A, JP-H11-149180-A, and JP-2000-292981-A describes that the resulting toner has a good combination of heat-resistant storage stability, low-temperature fixability, hot offset resistance, and image gloss.
JP-2002-55484-A discloses a method including subjecting a polymerizable monomer composition including a polymerizable monomer and a colorant to a polymerization in an aqueous medium to produce colored polymer particles, washing the colored polymer particles, removing water therefrom to obtain toner particles, containing the toner particles in a container that can be depressurized or heated, and subjecting the toner particles to a depressurizing-heating treatment by supplying saturated water vapor, superheated water vapor, or high-humidity air to the container so that unreacted polymerizable monomers are removed.
JP-2001-92180-A discloses a method including subjecting a polymerizable monomer composition including a polymerizable monomer and a colorant to a polymerization in an aqueous medium in the presence of a polymerization initiator, and introducing the air or an inert gas into a distillation apparatus so that unreacted polymerizable monomers are removed.
JP-2006-208624-A discloses a method including dispersing a polymerizable monomer composition including a polymerizable monomer in a dispersion medium, introducing a carrier gas to a polymer dispersion liquid obtained during the latter half or after the polymerization so that organic volatile components are removed from the polymer dispersion liquid.
However, in order to industrially manufacture spherical toner particles having a small particle diameter and a narrow particle diameter distribution, the above methods may be required to further improve the efficiency of organic solvent removal.